In the past, a printed circuit board (PCB) generally uses a single power management integrated circuit (PMIC) to provide a supply voltage to multiple ICs/components. IR drop (i.e. voltage drop) variation among ICs/components may be insignificant because a current sink of each IC/component is small. However, for higher performance ICs/components which have higher power consumption but still need to be supplied by a single PMIC, IR drop variation is getting more serious. Therefore, how to accurately compensate IR drop becomes an important topic.